Fix code formatting and linting issues

- Updated GitHub Actions workflow to use correct flake8 configuration
- Fixed line length issues by using 88 characters as configured
- Removed unused imports and trailing whitespace
- Fixed f-string placeholders and unused variables
- All linting checks now pass with project configuration

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

wikijs/models/base.py

@@ -3,19 +3,20 @@
 from datetime import datetime
 from typing import Any, Dict, Optional
 
-from pydantic import BaseModel as PydanticBaseModel, ConfigDict
+from pydantic import BaseModel as PydanticBaseModel
+from pydantic import ConfigDict
 
 
 class BaseModel(PydanticBaseModel):
     """Base model with common functionality for all data models.
-    
+
     Provides:
     - Automatic validation via Pydantic
     - JSON serialization/deserialization
     - Field aliases for API compatibility
     - Consistent datetime handling
     """
-    
+
     model_config = ConfigDict(
         # Allow population by field name or alias
         populate_by_name=True,
@@ -26,52 +27,50 @@ class BaseModel(PydanticBaseModel):
         # Allow extra fields for forward compatibility
         extra="ignore",
         # Serialize datetime as ISO format
-        json_encoders={
-            datetime: lambda v: v.isoformat() if v else None
-        }
+        json_encoders={datetime: lambda v: v.isoformat() if v else None},
     )
-    
+
     def to_dict(self, exclude_none: bool = True) -> Dict[str, Any]:
         """Convert model to dictionary.
-        
+
         Args:
             exclude_none: Whether to exclude None values
-            
+
         Returns:
             Dictionary representation of the model
         """
         return self.model_dump(exclude_none=exclude_none, by_alias=True)
-    
+
     def to_json(self, exclude_none: bool = True) -> str:
         """Convert model to JSON string.
-        
+
         Args:
             exclude_none: Whether to exclude None values
-            
+
         Returns:
             JSON string representation of the model
         """
         return self.model_dump_json(exclude_none=exclude_none, by_alias=True)
-    
+
     @classmethod
     def from_dict(cls, data: Dict[str, Any]) -> "BaseModel":
         """Create model instance from dictionary.
-        
+
         Args:
             data: Dictionary data
-            
+
         Returns:
             Model instance
         """
         return cls(**data)
-    
+
     @classmethod
     def from_json(cls, json_str: str) -> "BaseModel":
         """Create model instance from JSON string.
-        
+
         Args:
             json_str: JSON string
-            
+
         Returns:
             Model instance
         """
@@ -80,11 +79,11 @@ class BaseModel(PydanticBaseModel):
 
 class TimestampedModel(BaseModel):
     """Base model with timestamp fields."""
-    
+
     created_at: Optional[datetime] = None
     updated_at: Optional[datetime] = None
-    
+
     @property
     def is_new(self) -> bool:
         """Check if this is a new (unsaved) model."""
-        return self.created_at is None
+        return self.created_at is None